{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter_5 - 5-19C Energy can be transferred to or from a...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
5-19C Energy can be transferred to or from a control volume as heat, various forms of work, and by mass. 5-24E A water pump increases water pressure. The flow work required by the pump is to be determined. Assumptions 1 Flow through the pump is steady. 2 The state of water at the pump inlet is saturated liquid. 3 The specific volume remains constant. Properties The specific volume of saturated liquid water at 10 psia is /lbm ft 01659 . 0 3 psia 10 @ f v v (Table A-5E) Then the flow work relation gives Btu/lbm 0.1228 3 3 1 2 1 1 2 2 flow ft psia 5.404 Btu 1 10)psia /lbm)(50 ft 01659 . 0 ( ) ( P P P P w v v v 5-29C The kinetic energy of a fluid increases at the expense of the internal energy as evidenced by a decrease in the fluid temperature. 5-32 EES Problem 5-31 is reconsidered. The effect of the inlet area on the mass flow rate, exit velocity, and the exit area as the inlet area varies from 50 cm 2 to 150 cm 2 is to be investigated, and the final results are to be plotted against the inlet area. Analysis The problem is solved using EES, and the solution is given below. Function HCal(WorkFluid$, Tx, Px) "Function to calculate the enthalpy of an ideal gas or real gas" If 'Air' = WorkFluid$ then HCal:=ENTHALPY('Air',T=Tx) "Ideal gas equ." else HCal:=ENTHALPY(WorkFluid$,T=Tx, P=Px) "Real gas equ." endif end HCal "System: control volume for the nozzle" "Property relation: Air is an ideal gas" "Process: Steady state, steady flow, adiabatic, no work" "Knowns - obtain from the input diagram" WorkFluid$ = 'Air' T[1] = 200 [C] P[1] = 300 [kPa] Vel[1] = 30 [m/s] P[2] = 100 [kPa] Vel[2] = 180 [m/s] A[1]=80 [cm^2] Am[1]=A[1]*convert(cm^2,m^2) "Property Data - since the Enthalpy function has different parameters for ideal gas and real fluids, a function was used to determine h." h[1]=HCal(WorkFluid$,T[1],P[1]) h[2]=HCal(WorkFluid$,T[2],P[2]) "The Volume function has the same form for an ideal gas as for a real fluid." v[1]=volume(workFluid$,T=T[1],p=P[1]) v[2]=volume(WorkFluid$,T=T[2],p=P[2]) Water 10 psia 50 psia
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
"Conservation of mass: " m_dot[1]= m_dot[2] "Mass flow rate" m_dot[1]=Am[1]*Vel[1]/v[1] m_dot[2]= Am[2]*Vel[2]/v[2] "Conservation of Energy - SSSF energy balance" h[1]+Vel[1]^2/(2*1000) = h[2]+Vel[2]^2/(2*1000) "Definition" A_ratio=A[1]/A[2] A[2]=Am[2]*convert(m^2,cm^2) A 1 [cm 2 ] A 2 [cm 2 ] m 1 T 2 50 24.19 0.3314 184.6 60 29.02 0.3976 184.6 70 33.86 0.4639 184.6 80 38.7 0.5302 184.6 90 43.53 0.5964 184.6 100 48.37 0.6627 184.6 110 53.21 0.729 184.6 120 58.04 0.7952 184.6 130 62.88 0.8615 184.6 140 67.72 0.9278 184.6 150 72.56 0.9941 184.6 50 70 90 110 130 150 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 A[1] [cm^2] m [1]
Image of page 2
5-38E Air is decelerated in a diffuser from 600 ft/s to a low velocity. The exit temperature and the exit velocity of air are to be determined. Assumptions 1 This is a steady-flow process since there is no change with time. 2 Air is an ideal gas with variable specific heats. 3 Potential energy changes are negligible. 4 The device is adiabatic and thus heat transfer is negligible. 5 There are no work interactions.
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern